Apparatus for the manufacture of eccentric core/sheath conjugate filaments

ABSTRACT

Apparatus for the manufacture of sheath/core conjugate filaments in which the sheath component flows into a channel containing a dilobate end portion formed in a plateau on the surface of a spinneret plate and is extruded through an extrusion orifice contained in a counter-bore communicating with the dilobate channel, the core forming material being injected through a Dshaped orifice into the same counter-bore to yield a filament having an eccentrically located D-shaped core.

United States Patent [191 Bisset et al.

1 Dec. 11, 1973 APPARATUS FOR THE MANUFACTURE OF ECCENTRIC CORE/SHEATH CONJUGATE FILAMENTS [75] Inventors: Douglas Chisholm Bisset; Kenneth Mervyn Pugh, both of Pontypool, England [73] Assignee: Imperial Chemical Industries Limited, London, England [22] Filed: June 19, 1972 [21] Appl. No.: 263,905

[30] Foreign Application Priority Data June 18, 1971 Great Britain 28,765/71 [52] U.S. Cl. 425/131, 264/177 F, 425/463 [51] Int. Cl D01d 3/00 [58] Field of Search 425/131, 463; 264/177 F [56] References Cited UNITED STATES PATENTS 2,861,319 11/1958 Breen 425/131 UX Radow et a1. 425/131 UX Matsui et al. 425/131 X FOREIGN PATENTS OR APPLICATIONS 1,101,452 1/1968 Great Britain 425/131 Primary ExaminerRobert D. Baldwin Attorney-Thomas J. Morgan et a1.

[57] ABSTRACT Apparatus for the manufacture of sheath/core conjugate filaments in which the sheath component flows into a channel containing a dilobate end' portion formed in a plateau on the surface of a spinneret plate and is extruded through an extrusion orifice contained in a counter-bore communicating with the dilobate channel, the core forming material being injected through a D-shaped orifice into the same counter bore to yield a filament having an eccentrically located D- shaped core.

6 Claims, 6 Drawing Figures PATENTED BEE] 1 I975 SHEET 1 BF 2 APPARATUS FOR THE MANUFACTURE OF ECCENTRIC CORE/SHEATH CONJUGATE FILAMENTS The present invention is concerned with apparatus for the manufacture of eccentric core/sheath conjugate filaments having a defined core shape and uniform cross section.

Considerable attention has been paid to the design of apparatus for the production of core/sheath filaments especially such filaments in which the core is located eccentrically within the sheath and which, as a result, are capable of forming a crimped bulky structure usually following some form of heat relaxing treatment.

In a particularly desirable cross section the core component is essentially D-shaped and is located principally in one half of the filament, depending on the ratio of the components. Apparatus, that is spinneret assemblies, for the production of such filaments have been described in a number of patent specifications of which British Pat. Nos. 1,017,639; 1,101,452 and 1,148,773 are examples.

Particular problems encountered in the production of conjugate filaments of this type are in providing uniformity in cross section between and along individual filaments an in ensuring that the sheath component completely surrounds the core. This latter aspect is especially important when filaments are produced by the melt spinning techniques and have a core component which is of a significantly lower melting point than the sheath component, since in these circumstances if the sheath does not completely surround the core there is a tendency for filament fusion to occur during spinning and also in subsequent processing if heat is applied.

We have found that a particularly suitable assembly for the production of core/sheath conjugate filaments having eccentrically located D-shaped core, comprises a spinneret plate containing at least one plateau located on its upper surface in which there is formed channels of a defined shape and which communicate with a portion of the spinneret surface from which the sheath polymer flows. Extrusion orifices are located in counter bores formed in the spinneret plate at the closed ends of the said channels and a back plate is positioned above the spinneret plate and in contact with the plateaux, providing means supplying sheath forming polymer to the space between the said plate and the spinneret plate and containing D-shaped orifices aligned with the extrusion orifices in the spinneret plate. Means are also provided for supplying polymer to the D- shaped orifices of the said back plate.

Accordingly, therefore, the present invention provides a spinneret assembly for the manufacture of a sheath/core conjugate filament having an eccentricaly located D-shaped core, comprising a spinneret plate having an upper and lower face, at least one plateau located on the said upper face in which plateau is formed a channel having a closed end portion and containing an extrusion orifice counter-bore communicating with an extrusion orifice formed in the lower face of the spinneret plate, a back plate positioned above the spinneret plate and having a lower surface in contact with the said plateau to define a space between the lower surface of the back plate and the upper face of the spinneret plate, which space communicates with the said channel formed in the plateau, means within the back plate adapted to supply sheath forming polymer to the said space between the lower surface of the back plate and the upper face of the spinneret plate and further means within the back plate located above the spinneret counter-bore for injecting a core forming polymer into the said counter-bore, which means includes a D-shaped orifice formed in the lower surface of the said back plate.

In such apparatus the flat of the D in the D-shaped orifices contained in the back plate is perpendicular to the line of flow of the sheath polymer in the channels and in the horizontal plane and the said orifices have a diameter which is preferably equal to or less than the diameter of the extrusion orifice counter-bores.

The channels formed in the plateau should preferably have dilobate end portions to control the flow of sheath forming polymer uniformly around the curved outer portion of the core component.

The exact position of the extrusion orifice counterbores relative to the channels will depend, inter alia, on the ratios of the components and any difference in their melt viscosities.

In order to enable the invention to be readily understood, one embodiment will now be described with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic representation of a cross section of a spinneret assembly according to the present invention.

FIG. 2 is an enlarged sectional view of the channel arrangement of FIG. 1.

FIG. 3 is an enlarged sectional view of a modified channel arrangement.

FIGS. 4 and 5 are cross sections of filaments spun using the apparatus of FIGS. 1 and 2.

FIG. 6 is a cross section of the filament formed using other apparatus.

Referring to FIGS. 1 and 2, a pack holder 1 contains a spinneret plate 2 having a raised centre plateau 3 in which are formed dilobate channels 4 having lobes 4a and 4b. Extrusion orifices 5 are formed in the base of counter-bores 6 located in the end portions of channels 4. A back plate 7 is positioned in contact with the plateau 3 and defines an annular space 8 between the two plates. Polymer supply channels 9 are provided to communicate with annular space 8. D-shaped orifices 10 are formed in the plate vertically above the extrusion orifice counter-bores 6. A distributor plate 11 is positioned behind the back plate and contains polymer supply chambers 12 and 13. Supply ports 14 communicate with chamber 12 and supply channels 9 in the back plate. Supply ports 15 communicate with chamber 13 and a recess 16 formed in the underside of the distributor plate which permits supply of polymer to the D- shaped orifices 10.

Preferably there is one sheath polymer supply channel 9 feeding the annular space 8 adjacent to each channel 4.

In the representation of the channels shown in FIG. 2, to which reference has been made above, the counter-bore 6 contacts the point of intersection of the lobes 4a and 4b. The position of the D-shaped orifices in the back plate relatively to the counter-bore is shown in dotted outline.

In FIG. 3 the counter-bore is spaced apart from the point of intersection of the lobes of the channel to provide additional space for sheath forming polymer to reach the back of the orifice.

FIG. 4 is a cross section of a filament produced using the apparatus of FIGS. 1 and 2 in which the polymer components are present in equal amounts, the said filament having a core 20 and a sheath 21.

In FIG. 5 the sheath 3t and core 31 components are present in a 70/30 ratio.

Filaments shown in a cross section in FIG. 6 having cores 40 and sheaths 41 were produced by apparatus other than that of the present invention.

Eccentric core/sheath filaments in which the core and sheath components are present in equal proportions are formed from a 66 nylon homo-polymer and a 66/6/6iP (80:101l0) copolymer using the apparatus of FIGS. 1 and 2. The 66 polymer is introduced into the annular chamber 12 where it passes through supply ports 14 in the distributor plate into supply channels 9 in the back plate and thence annular space 8 from where it flows into channels 4 and counter-bores 6. The 66/6/6iP core component is forced from chamber 13 through supply ports 15 into the recess 16 and is then injected by the D-shaped orifice 10 through the sheath polymer contained in channel 4 into the extrusion Oflfice counter-bore 6. The two polymers are then extruded through extrusion orifices 5 into conjugate filaments having the cross section shown in FIG. 5.

When the ratio of the polymer components is changed to 70/30 core/sheath it is necessary to use the channel arrangement of FIG. 3 in order that the sheath flow encompasses the core component and thus prevents fusion of filaments after extrusion.

As an additional aid to ensuring a complete sheath is formed around the conjugate filament the portion of the plateau 3 surrounding the channel 4 may be machined away. This will then allow the sheath polymer to flow into the channel in a very limited amount from all directions.

If the core component is merely injected through the sheath polymer when the latter is not contained in a channel to control its flow around the extrusion orifice, the filaments have a cross section similar to that shown in FIG. 6. In these filaments the core 40 has a pinchedin appearance and the thickness of the sheath is not uniform around the curved portion of the core, thus the degree of eccentricity of the core component in relation to the sheath which can be achieved is reduced.

What we claim is:

l. A spinneret assembly for the manufacture of a sheath/core conjugate filament having an eccentrically located D-shaped core, comprising a spinneret plate having an upper and lower face, at least one plateau located on the said upper face in which plateau is formed a channel having a closed end portion surrounding an extrusion orifice counter-bore communicating with an extrusion orifice formed in the lower face of the spinneret plate, a back plate positioned above the spinneret plate and having a lower surface in contact with the said plateau to define a space between the lower surface of the back plate and the upper face of the spinneret plate, which space includes the said channel formed in the plateau, means within the back plate adapted to supply sheath forming polymer to the said space between the lower surface of the back plate and the upper face of the spinneret plate and further means within the back plate located above the spinneret counter-bore for injecting a core forming polymer into the said counter-bore, which means includes a D-shaped orifice formed in the lower surface of the said back plate.

2. A spinneret assembly according to claim 1, wherein the channel has a dilobate end portion.

3. A spinneret assembly according to claim 2, wherein the D-shaped orifice has its flat portion perpendicular to the horizontal axis of the channel and in the horizontal plane.

4. A spinneret assembly according to claim 2, wherein the diameter of the D-shaped orifice is equal to or less than the diameter of the spinneret counterbore.

5. A spinneret assembly according to claim 1, wherein the said assembly contains a plruality of channels and the back plate contains an equivalent number of means for supplying sheath and core forming polymer, and means supplying the sheath forming polymer being located adjacent the channels.

6. A spinneret assembly according to claim 1, wherein the plateau located on the upper face of the spinneret plate is not in contact with the lower surface of the back plate in the area surrounding the channel formed in the said plateau to allow the sheath polymer to flow into the channel in a very limited amount from all directions. 

1. A spinneret assembly for the manufacture of a sheath/core conjugate filament having an eccentrically located D-shaped core, comprising a spinneret plate having an upper and lower face, at least one plateau located on the said upper face in which plateau is formed a channel having a closed end portion surrounding an extrusion orifice counter-bore communicating with an extrusion orifice formed in the lower face of the spinneret plate, a back plate positioned above the spinneret plate and having a lower surface in contact with the said plateau to define a space between the lower surface of the back plate and the upper face of the spinneret plate, which space includes the said channel formed in the plateau, means within the back plate adapted to supply sheath forming polymer to the said space between the lower surface of the back plate and the upper face of the spinneret plate and further means within the back plate located above the spinneret counter-bore for injecting a core forming polymer into the said counter-bore, which means includes a D-shaped orifice formed in the lower surface of the said back plate.
 2. A spinneret assembly according to claim 1, wherein the channel has a dilobate end portion.
 3. A spinneret assembly according to claim 2, wherein the D-shaped orifice has its flat portion perpendicular to the horizontal axis of the channel and in the horizontal plane.
 4. A spinneret assembly according to claim 2, wherein the diameter of the D-shaped orifice is equal to or less than the diameter of the spinneret counter-bore.
 5. A spinneret assembly according to claim 1, wherein the said assembly contains a plruality of channels and the back plate contains an equivalent number of means for supplying sheath and core forming polymer, and means supplying the sheath forming polymer being located adjacent the channels.
 6. A spinneret assembly according to claim 1, wherein the plateau located on the upper face of the spinneret plate Is not in contact with the lower surface of the back plate in the area surrounding the channel formed in the said plateau to allow the sheath polymer to flow into the channel in a very limited amount from all directions. 